Coconuts: all they're cracked up to be?

A new study showing that coconut oil prevents tooth decay has added to the recent enthusiasm for all things coconut – not that Miranda Kerr, who is a committed devotee, needs reminding.

The model last year piqued public interest in virgin coconut oil when she revealed that she will not go a day without it.

"I personally take four teaspoons per day, either on my salads, in my cooking or in my cups of green tea" she said.

But, as much as many have flocked to health-food shops with the hope of tapping into Kerr’s secret weapon, do new health claims about the once-maligned coconut oil and its trendy sibling, coconut water, stand up to scrutiny?

Researchers at the Athlone Institute of Technology in Ireland say coconut oil treated with enzymes attacks Streptococcus bacteria – a major cause of tooth decay.

"Incorporating enzyme-modified coconut oil into dental hygiene products would be an attractive alternative to chemical additives," Dr Damien Brady last week told the Society for General Microbiology conference at the University of Warwick in Coventry, England.

The study also found that enzyme-modified coconut oil was active against the yeast Candida albicans, which can cause thrush and other health problems.

After decades of warnings about its alleged artery-clogging properties, recent studies suggest that coconut oil may in fact be heart friendly and could have many other health benefits.

"For more than 60 years, health officials and the media have warned that saturated fats are bad for your health and lead to a host of negative consequences, including high cholesterol, obesity, heart disease and Alzheimer’s disease," says best-selling author and Huffington Post blogger, Dr Joseph Mercola.

"It may surprise you to learn that the naturally occurring saturated fat in coconut oil is actually good for you and provides a number of profound health benefits, including improving heart health, supporting your immune system, boosting your thyroid and improving your skin.

"Nearly 50 percent of the fat in coconut oil is of a type rarely found in nature called lauric acid, a ‘miracle’ compound that your body converts into monolaurin, which has anti-viral and anti-bacterial properties," says Dr Mercola.

Thomas Brenna, a professor of nutritional sciences at Cornell University, agrees. He told The New York Times: "Most of the [earlier] studies involving coconut oil were done with partially hydrogenated coconut oil, which researchers used because they needed to raise the cholesterol levels of their rabbits in order to obtain certain data".

"Virgin coconut oil, which has not been chemically treated, is a different thing in terms of health perspective," says Dr Brenna.

A recent study by Sydney’s Garvan Institute of Medical Research (GIMR) found that a diet rich in coconut oil reduces the risk of developing Type 2 diabetes by protecting against “insulin resistance” and avoiding the buildup of body fat.

"These findings are important because obesity and insulin resistance are major factors leading to the development of Type 2 diabetes," say GIMR researchers Dr Nigel Turner and Associate Professor Jiming Ye.

"Coconut oil has dragged itself out of the muck of vast misrepresentation over the past few years but still rarely gets the appreciation it truly deserves," according to Sayer Ji, founder of US natural medicine database GreenMedInfo.com.

While coconut oil and coconut milk are extracted from the kernel or meat of mature coconuts harvested from the coconut palm, coconut water is the liquid found inside young green coconuts.

The coconut water craze - backed by celebrity investors including Madonna, Demi Moore and Matthew McConaughey - has snowballed in the US and Europe with sales doubling to $US265 million last year and expected to double again this year.

More than 15 brands have been launched on the Australian market in the past 12 months and bottles, cans and Tetra Paks of coconut water are increasingly visible on supermarket shelves.

"There are few beverages on this planet as biocompatible to the human body and its hydration needs as coconut water,” says Ji, who notes that coconut water has even been used for intravenous hydration of critically ill patients in remote areas.

"While some are concerned about the sugar content of this slightly sweet beverage, recent research shows that it actually exhibits blood sugar lowering properties," Ji says.

Academy of Nutrition and Dietetics spokesperson and dietician Andrea Giancoli explains: "The big deal about coconut water is that it packs a potassium punch, and potassium is important for heart health, regulating blood pressure and other body systems".

But coconut water is not "magical," Giancoli told National Public Radio, "and there’s plenty of potassium in a healthy diet."

New industry body Coconut Water Australia says coconut water is "the purest liquid second only to water itself…choc-full of electrolytes, calcium, potassium, magnesium: everything that is good for you for only around 60 calories per serve."

"While the marketing on the packages claims coconut water is a nutritional goldmine," Choice found that dietary consultants believed very differently: "…the only real goldmine is for those selling the product."

Dietician Tania Ferraretto told the watchdog that coconut water has been promoted as a source of minerals such as calcium, magnesium and phosphorous, "but it only contains small amounts of these and other nutrients."

Instead, Ferraretto recommends plain water: "It’s the best drink to hydrate the body and it’s free, unlike coconut water, which can cost up to $4 a bottle."